Corrosive resistant pump



y 14, 1953 s. H. s. RAUB El'AL 3,089,423

CORROSIVE RESISTANT PUMP Filed Nov. 25, 1960 2 Sheets-Sheet 1 INVENTORSSAMUEL H. S. RAUB EDWIN S. MALKIN WILLIAM J. ALTON A T TORNEV May 14,1963 s. H. s. RAUB ETAL CORROSIVE RESISTANT PUMP 2 Sheets-Sheet 2 FiledNov. 25, 1960 INVENTORS SAMUEL H. 5. RAUB EDWIN S. MALKIN Wll.

LIAM J. LJZQN w! ATTORNEY United States Patent 3,089,423 CORROSIVERESISTANT PUMP Samuel H. S. Raub, Bay Village, Ohio, Edwin S. Mallqn,

Wilton, Conn., and William J. Alton, Cleveland, Ohio,

assignors to Union Carbide Corporation, a corporation of New York FiledNov. 25, 1960, Ser. No. 71,548 Claims. (Cl. 103-87) This inventionrelates to corrosive resistant centrifugal pumps composed, for example,of impervious graphite for use specifically with corrosive liquids, andmore particularly it concerns improvements in pumps of this character.

A corrosive resistant centrifugal pump which has enjoyed great successfor transporting corrosive liquids in the chemical industry is disclosedand claimed in United States Patent No. 2,858,768, issued to W. M.Gaylord, in, et al. on November 4, 1958. Difficulty, however, has beenencountered with a pump of this type owing principally to theover-zealousness of the customer to perform proper maintenance upon thepump. For example, the customer when making an inspection of the pumpcommonly may find a slight amount of leakage resulting from normal wearof the rubbing parts of the seal assembly. It has been the customerspractice to tighten all the adjustments provided for the seal assemblymainly because the construction of the assembly is such that it isdifiicult to know through which of its parts leakage has occurred. Thispractice has at times brought undue pressure to bear upon the parts ofthe seal assembly which interferes with their proper function, if noteventually causing their fracture, they being composed of imperviousgraphite, for example. Another difiiculty has been that of preventingliquid leakage from coming into contact with metal parts of the pump andcorroding them, and of properly cooling the rubbing parts of the sealassembly in order to prevent abnormal wear during operation of the pump.

It is therefore the principal object of the invention to simplify andimprove upon the construction of the seal assembly for pumps of theabove referred type.

A more specific object is to provide for greater facility on the part ofthe customer to detect even the slightest leakage from the pump andthrough what parts of the assembly leakage has occurred and also toprovide for more convenient adjustments for the customer to make inorder to eliminate leakage, even while the pump is still operating.

Another object is to provide for entrapment of leakage which may occurwithin the seal assembly and for carrying such leakage away withoutcontact with metal parts of the pump.

Still another object is to provide for flushing of the seal assemblywith a coolant in order to prolong the wear life of rubbing parts of theassembly.

Yet another object is to provide for fewer metal parts to be used withinthe seal assembly than heretofore employed.

These objects are attained by the invention which comprises an improvedseal assembly for a corrosive resistant centrifugal pump of the abovereferred type. The seal assembly is composed of a corrosive resistantmaterial, for example, impervious graphite, and comprises a rotary sealring secured to a shaft sleeve provided onto the shaft which drives thepump and a stationary seal ring mounted within the volute cover of thepump, the rotary and stationary seal rings providing therebetween aprimary seal, and a non-rotating seal ring adaptor secured to thestationary seal ring by an adjustable metal follower plate. The adaptorprovides an annular chamber for entrapping leakage through the primaryseal and also provides secondary seal for the pump operable throughrotation of the "ice shaft. Drainage means are provided to the seal ringadaptor together with means for a coolant.

1n the drawings:

FIG. 1 is a perspective view of a corrosive resistant centrifugal pumpembodying the invention;

FIG. 2 is a vertical elevation partially in section of the pump shown inFIG. 1;

FIG. 3 is an enlarged detail of a portion of FIG. 2;

FIG. 4 is an enlarged perspective view of a part only of the shaftsleeve shown in FIG. 2;

FIG. 5 is a perspective view of the follower plate for mounting of theseal ring adaptor shown in FIG. 2; and

FIG. 6 is a perspective view of a rubber compression ring employed inconjunction with the follower plate shown in FIG. 5.

Referring to the drawings, there is shown a corrosive resistantcentrifugal pump of the type referred to above but embodying theprinciples of the invention. As there shown, the pump comprises a volutecasing V and cover C both of impervious graphite, for example, which aresupported by a unitary metal casting, preferably iron, comprising amotor engaging flange B, a volute supporting flange F, and struts Htherebetween, forming a hollow open sided barrel shaped casting. Themotor engaging flange B is bolted to the frame of a motor M mounted on afoundation N. The volute casing V and cover C are bolted betweenthe'flange F and a metal cover flange T. A discharge flange G is boltedto the top of flanges F and T, and a suction nozzle Z is bolted to thecover flange T. The flange F and cover flange T have cast holes forbolts 12, and both have T slots 20 receiving standard square head boltsfor the discharge flange G. The cover flange T has similar slots 22, formounting the suction nozzle Z.

The motor M has a motor shaft D on which is sleeved an impeller shaft Sof stainless steel. The impeller shaft S passes through registeredcentral apertures in the flange F and volute cove-r C and has securedthereto an impervious.

graphite impeller I which rotates inside the volute casing V. Thus, itwill be seen that the pump is of a type which fastens to the frame ofthe motor and uses the bearings of the motor, it having none of its own.

The motor shaft D is hollow and is. mounted in motor bearings 2-4 in themotor frame, and the impeller shaft S has a close tolerance slip fltover an extension provided on the motor shaft, seating on and keyed tomilled shoulders 26. A drawbolt 28 having its head outside of the motorpasses through the hollow motor shaft D and is screwed into threads 30*within the bored end of the impeller shaft S, thus providing for easyremoval of the impeller and its shaft. to the impeller shaft S in anyconventional fashion, for example, by threading it on.

In accordance with the invention, the pump is provided with a sealassembly liquid-tightly secured within the volute cover C as shown inFIGS. 2 and 3. As shown, a shaft sleeve 34 of impervious graphite isprovided-onto the impeller shaft S and separates the shaft from the sealassembly. The shaft sleeve 34 has an enlarged diameter end provided withthreads onto which is secured the impeller I, as at 36. A rotary sealring 38 of impervious graphite similarly is secured onto the shaftsleeve 34 behind the impeller I and is of a diameter slightly less thanthe registered aperture in the volute cover C so as to rotate freelytherein.

The rotary seal ring 38 rotates against a stationary seal ring 40 alsocomposed of impervious graphite, the rubbing interfaces of which providea primary seal for the pump. The stationary seal ring 40 is partlysecured within the volute cover C by a gland nut 42 threaded into thecover, as at 44. A packing box 46 composed, for example, of

corrosive resistant plastic gaskets, is compressed by the I The impellerI may be mounted,

3 gland nut 42 and prevents against leakage between the stationary sealring 46 and volute cover C.

Mounted behind the stationary seal ring 40 is an impervious graphitenon-rotating seal ring adaptor 50. The adaptor 50 has an inside diameterlarger than the diameter of the shaft sleeve 34 and defines an annularchamber 52 for entrapping leakage. At its outer end, the adaptor 50 hasa reduced diameter neck providing a close tolerance but free rotatingfit with the shaft sleeve 34- which passes through it. The adaptor 50 iskeyed to the stationary seal ring 40 through pins 54 and fitted over theneck of the adaptor 50 is a metal follower plate 56 secured to the metalflange F by bolts, shown in broken lines in the drawing. The followerplate 56 prevents rotation of both the stationary seal ring 40 andadaptor 50 and secures them tightly within the volute cover C. A rubbercompression ring 58 dampens vibration of the follower plate 56 andreduces stress upon the adaptor 50.

The shaft sleeve 34 at its outer end has spiral grooves 60 whose helixis directed opposite to rotation of the sleeve with the impeller shaft Sas shown in FIG. 4. The spiral grooves 60 in conjunction with the closetolerance but free rotating fit of the shaft sleeve 34 within the neckof the adaptor 50 actually provide a pumping action which in effect is asecondary seal for the pump. A preferred contour for the spiral grooves60, as best shown in FIG. 3, consists of a rounded bottom V shapedgroove in which the side of the groove nearest the impeller is thelonger.

Drainage means 70 are provided to the adaptor 50 and serve to carry offleakage from Within the chamber 52 without contact with metal parts ofthe pump. Inlet means 72 may also be provided for flushing the chamber52 with a coolant, for example, water, in order to prevent Wear of therubbing surfaces of both the rotary and stationary seal rings 38 and 40.

The collection of liquid drainage through drainage means 70 is anindication to the customer operating the pump that tightening of theseal assembly is needed. This can be quite simply achieved by tighteningdown upon the bolts which secure the metal follower plate 56 to theflange F. Similarly, leakage through the packing box 46, in dicated bythe presence of leakage on the outside surfaces of the seal assembly,can be eliminated by tightening of the gland nut 42. To carry away fromthe plate F such leakage as may occur past the packing box 46, the coverC is provided with a drip lip 76. For a similar purpose, the adaptor 50is also provided with a drip lip 78 at its outer end. Thus, it will beappreciated that a customer operating the pump has greater facility forobserving leakage from the pump upon periodic inspection and fordetermining the several sources from which it may occur, and is alsoprovided with more convenient adjustments for eliminating leakage, evenwhile the pump is still operating.

It will, of course, be understood that various adaptations andmodifications of the pump herein described may be made without departingfrom the spirit and scope of the invention.

What is claimed is:

1. In a corrosive resistant pump including a hollow metal casing havinga volute support flange and a motor engaging flange, a volute casing andcover of a corrosive resistant material mounted to said volute supportflange, a motor mounted to said motor engaging flange and an impellerwithin said volute casing secured to a shaft driven by said motor; theimprovement which comprises a seal assembly of a corrosive resistantmaterial comprising, in combination, a shaft sleeve provided onto saidshaft and rotatable therewith, said shaft sleeve having spiral groovemeans provided thereon at an end remote from said impeller, a rotaryseal ring secured to said shaft sleeve and a stationary seal ringmounted within said cover, said rotary and stationary seal ringsproviding therebetween a primary seal for said pump, a seal ring adaptorpositioned to said stationary seal ring, said adaptor being of adimension larger than said shaft sleeve and providing therewith anannular chamber for entrapment of leakage through said primary seal,said spiral groove means on said shaft sleeve cooperating through aclose but free running fit with said adaptor to define a secondary sealfor said pump operable through rotation of said shaft, and means forpreventing rotation of both said stationary seal ring and said adaptorand for securing them within said volute cover.

2. A corrosive resistant pump as defined by claim 1 in which saidadaptor is provided with drainage means.

3. A corrosive resistant pump as defined by claim 1 in which saidadaptor is provided with inlet means for a coolant.

4. A corrosive resistant pump as defined by claim 1 in which saidcorrosive resistant material is impervious graphite.

5. A corrosive resistant pump as defined by claim 1 in which said meansfor preventing rotation of said stationary seal ring and said adaptorcomprises a metal follower plate secured to said metal casting.

6. A corrosive resistant pump comprising, in combination, a hollow metalcasting having a volute support flange and a motor engaging flange, avolute casing and cover of a corrosive resistant material, a metal coverflange, said volute casing and cover being mounted between said coverand support flange, a motor mounted to said motor engaging flange andhaving a motor drive shaft, an impeller shaft driven by said motor driveshaft, a shaft sleeve of a corrosive resistant material provided ontosaid impeller shaft and rotatable therewith, an impeller secured to oneend of said shaft sleeve within said volute casing, said shaft sleevehaving spiral groove means provided thereon at an end remote from said 7impeller, the helix of said spiral groove means being directed oppositeto rotation of said impeller shaft, a rotary seal ring secured to saidshaft sleeve and a stationary seal ring mounted to said cover, saidrotary and stationary seal rings being composed of a corrosive resistantmaterial and providing therebetween a primary seal for said pump, a sealring adaptor of a corrosive resistant material keyed to said stationaryseal ring, said adaptor being of a dimension larger than said shaftsleeve and providing therewith an annular chamber for entrapment of leakage though said primary seal, said spiral groove means on said shaftsleeve cooperating through a close but free running fit with saidadaptor to define a secondary seal for said pump operable throughrotation of said impeller shaft, a metal follower plate mounted to saidadaptor and secured to said metal casting for preventing rotation ofboth said stationary seal ring and said adaptor, and drainage meansprovided to said adaptor for carrying leakage out of said chamberwithout contact with metal parts of said pump.

7. A corrosive resistant pump as defined by claim 6 in which saidadapter is provided with inlet means for a coolant.

8. A corrosive resistant pump as defined by claim 6 in which saidfollower plate is insulated from said adaptor by a rubber compressionmember.

9. A corrosive resistant pump as defined by claim 6 in which saidstationary seal ring is sealed against leakage within said volute coverby a packing box and in which said packing box is secured within saidvolute cover by a gland nut.

10. A corrosive resistant pump as defined by claim 6 in which saidcorrosive resistant material is impervious graphite.

References Cited in the file of this patent UNITED STATES PATENTS

1. IN A CORROSIVE RESISTANT PUMP INCLUDING A HOLLOW METAL CASING HAVINGA VOLUTE SUPPORT FLANGE AND A MOTOR ENGAGING FLANGE, A VOLUTE CASING ANDCOVER OF A CORROSIVE RESISTANT MATERIAL MOUNTED TO SAID VOLUTE SUPPORTFLANGE, A MOTOR MOUNTED TO SAID MOTOR ENGAGING FLANGE AND AN IMPELLERWITHIN SAID VOLUTE CASING SECURED TO A SHAFT DRIVEN BY SAID MOTOR; THEIMPROVEMENT WHICH COMPRISES A SEAL ASSEMBLY OF A CORROSIVE RESISTANTMATERIAL COMPRISING, IN COMBINATION, A SHAFT SLEEVE PROVIDED ONTO SAIDSHAFT AND ROTATABLE THEREWITH, SAID SHAFT SLEEVE HAVING SPIRAL GROOVEMEANS PROVIDED THEREON AT AN END REMOTE FROM SAID IMPELLER, A ROTARYSEAL RING SECURED TO SAID SHAFT SLEEVE AND A STATIONARY SEAL RINGMOUNTED WITHIN SAID COVER, SAID ROTARY AND STATIONARY SEAL RINGSPROVIDING THEREBETWEEN A PRIMARY SEAL FOR SAID PUMP, A SEAL RING ADAPTORPOSITIONED TO SAID STATIONARY SEAL RING, SAID ADAPTOR BEING OF ADIMENSION LARGER THAN SAID SHAFT SLEEVE AND PROVIDING THEREWITH ANANNULAR CHAMBER FOR ENTRAPMENT OF LEAKAGE THROUGH SAID PRIMARY SEAL,SAID SPIRAL GROOVE MEANS ON SAID SHAFT SLEEVE COOPERATING THROUGH ACLOSE BUT FREE RUNNING FIT WITH SAID ADAPTOR TO DEFINE A SECONDARY SEALFOR SAID PUMP OPERABLE THROUGH ROTATION OF SAID SHAFT, AND MEANS FORPREVENTING ROTATION OF BOTH SAID STATIONARY SEAL RING AND SAID ADAPTORAND FOR SECURING THEM WITHIN SAID VOLUTE COVER.